The present invention relates to target meters.
Target meters operate on the principle that the force acting on a body suspended within a conduit in which fluid flows is related to the mass flow rate of the fluid. Velocity changes around the body result in pressure changes and the drag force on the body results from the pressure differences between the upstream and downstream surfaces. A known target meter comprises a drag plate situated within a conduit which is attached to a support member which extends to the outside of the conduit and is pivotable relatively to the conduit about a fulcrum. The force acting on the support tube, and tending to turn it about the fulcrum, is measured. Such a target meter is shown and described in section 3.2.7.3 of British Standard BS 7405. A disadvantage of the known target meter is that it has a non-linear response. Also, the fulcrum is prone to damage.